Abstract: The present invention relates to a method detection of microorganisms concentrated from body fluids as serum, sputum, pericardiac fluid, urine or other fluid on the surface of retaining membranes by specific partners of reaction that bind to antigenic components of the retained organisms is facilitated when the organisms in suspension in body fluids and/or concentrated on the membrane are treated with a high molar concentration of a chaotropic agent as guanidine, urea, isothiocyanate, thiourea.

Abstract: An interspecific antigen of Mycobacteria consists essentially of a mixture in substantially immunochemically pure form of a protein having a molecular weight of at least about 4.times.10.sup.6 Daltons and polysaccharide having a molecular weight of at least about 1.times.10.sup.6 Daltons, and has when subjected to cross-electrophoresis an immunoelectrophoretic precipitation pattern corresponding to A60-antigen of Mycobacteria bovis strain BCG. This antigen is effective for detecting the prior exposure of a subject to Mycobacterial infections by a cutaneous test.

Abstract: The sensitivity of hemagglutination inhibition tests is improved by introducing a determined amount of lyophilized antigen or antibody into serological tubes in the absence of the indicator component. The test fluid to be analyzed is incubated solely in the presence of its binding partner in a liquid phase. After completion of the binding reaction (about 5 hours but extendable to 18 hours), the sensitized indicator solid phase, usually consisting of sensitized red blood cells, is added. By this process a 10 to 20 fold increase in sensitivity of the hemagglutination inhibition test is routinely achieved.